Internal combustion engine, particularly otto engine

ABSTRACT

A multiple cylinder internal combustion engine comprising an exhaust recycling system including an exhaust return line connected with an exhaust manifold of the internal combustion cylinder and exhaust metering device comprising a first metering member connected with a throttle valve of an intake manifold for joint actuation therewith and a plurality of turbulence nozzles, each of the turbulence nozzles being located in an immediate vicinity of an inlet valve of each combustion cylinder communicating a combustion chamber of a respective combustion cylinder with the intake manifold, the exhaust recycling system further comprising a header reservoir located downstream of said first metering member, and a plurality of separate exhaust return lines communicating the header reservoir with the plurality of turbulence nozzles, respectively.

BACKGROUND OF THE INVENTION

The invention relates to an internal combustion engine, particularly anOtto engine.

Exhaust recycling systems are provided in internal combustion engines,particularly in so-called Otto engines, for reducing emission ofpollutants with the exhaust, particularly nitric oxide. Formation ofnitric oxides is dependent on temperature and the oxygen content in thecombustion chamber of combustion cylinders. By mixing the exhaust with afuel-air mixture, both are reduced and the pollutant emission isdecreased.

In a known exhaust recycliner system for an Otto engine with carburetor,a second metering member is designed as an annular throttle whichconnects an exhaust return line with an intake manifold downstream ofthe carburetor. The exhaust is fed under excess pressure to thegasoline-air mixture in the intake manifold via this annular throttle.The first metering member arranged upstream of change to the secondmetering member in the exhaust recycling flow, is constructed as athrottle valve which is coupled with the carburetor throttle valve by arod linkage. At a low intake pipe pressure determined by the position ofthe carburetor throttle valve, the recycling portion of the exhaust fedto the intake manifold is determined by a position of the throttle valvein the exhaust return line. This throttle valve becomes inactive at apredetermined intake pipe pressure, and the exhaust recycling portion isexclusively determined by the annular throttle and decreases as theintake pipe pressure increasing. It is only permissible to recycle arelatively small amount of the exhaust with this exhaust recyclingsystem is a drop in the output of the internal combustion engine is tobe avoided.

SUMMARY OF THE INVENTION

The object of the invention is to provide, the internal combustionengine, in which the mixture preparation for every cylinder issubstantially improved, particularly when the fuel is injected into theinlet chamber by a so-called Jetronic, by direct feed of the hot exhaustflowing out of the exhaust return line at high flow velocity to theindividual inlet valves. The object of the invention is achieved byforming the second proportioning member which is located downstream ithe exhaust recycling flow, as a unit comprising a plurality ofturbulence nozzles, one nozzle for each cylinder. A header reservoir isconnected downstream of the first proportioning member in the exhaustrecycling flow, and separate exhaust return line connect the headerreservoir with the turbulence nozzles. The turbulence nozzles produce avery high charging motion in the combustion chamber. The combustion ofthe fuel-air mixture in the combustion chambers is accordinglysubstantially improved as a whole, so that a higher exhaust recyclingrate can be provided at the same output, which leads to a saving of fuelduring every cylinder charge. The internal combustion engine as a wholerequires less fuel, already leading to a reduction of the pollutantemission, which is then further reduced with the exhaust recyclingsystem. Turbulence nozzles are known and are used for feeding by-passair into the combustion chamber of combustion cylinders.

The recycling exhaust is only fed via a turbulence nozzle in eachinstance which is associated with a respective cylinder executing anintake stroke. This increases the discharge flow speed of the exhaust tothe turbulence nozzle and, accordingly, the effect on the chargingmovement of the mixture fed to the combustion chamber of the respectivecylinder of the internal combustion engine.

In an advantageous manner, moreover, the air supply via the intake pipeis in no way impeded, the density of the charge of the combustionchambers is improved and a very accurate control of the exhaustrecycling volume is achieved. This also relies on the fact that noexhaust reaches the intake conduit or is introduced there in anuncontrolled manner as long as the respective cylinder does notcommunicate with the intake conduit for the purpose of suction.

By shifting the first metering member to the exhaust manifold and,accordingly, into the area of high temperature, contamination of thefirst metering member with impurities, soot and condensation depositswhich occur in the cooled-down exhaust. The first proportioning member,which is constructed as a controlling mechanism, e.g. throttle valve ormetering valve, accordingly, has a longer service life, and the drift ofthe exhaust recycling rate is smaller.

Providing a temperature-controlled valve, preferably a bimetal valve, inthe exhaust return line directly at its branching off from the exhaustmanifold prevents exhaust recycling when the internal combustion engineis cold, since the valve keeps the exhaust return line closed during thehot-running of the internal combustion engine.

Supply of more or less high exhaust recycling rates delays the ignitionof the mixture in the combustion chamber, which is compensated for by acorresponding shifting forward of the ignition time, that is, theignition angle α_(Z). As a result of impurities and deposits in themetering members, a decrease in the exhaust recycling amounts cannot beavoided, at least in the long run, while the metering members remainunchanged. When the ignition angle is constantly shifted forwardpre-ignition, overheating, and finally destruction of the combustionpistons occur. This is prevented, according to another feature of theinvention, by regulating the ignition points to optimal combustionposition in the combustion chamber with an electronic control device, towhich in addition to other parameters for controlling the ignition angleand the injection period in injection systems, such as throttle valveposition, speed and temperature, also communicated configuration of thecombustion process in the combustion chambers. This combustionconfiguration can be detected optically in a known manner in that thelight configuration in the combustion chamber is measured by a sparkplug with built-in translucent rod. The optimal ignition point isreached when the light maximum occurs at a predetermined time. However,it is also possible to detect the combustion configuration by measuringthe pressure in the combustion chamber, where the ignition time is, inturn, characterized by the time of the pressure maximum.

According to another feature of the invention, the air index measured bya lambda probe in the exhaust manifold, is also communicated to theelectronic control device. The electronic control device then adjuststhe ignition angle α_(Z) and the injection period t_(i) in such a waythat λ=1. The lowest possible pollutant emission values can then beachieved with a catalytic convertor located downstream of the exhaustmanifold.

The present invention as to its construction so to its mode of operationwill be best understood from the following description with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal sectional view of a first embodiment of aninternal combustion engine with an exhaust recycling system invention;

FIG. 2 shows a longitudinal section view of a second embodiment of aninternal combustion engine according to the invention;

FIG. 3 shows a cross-sectional view of a header reservoir used ininternal combustion engines shown in FIGS. 1 and 2 and combined with adistributor; and

FIG. 4 shows a cross sectional view of a second embodiment of the headreservoir with distributor.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A combustion cylinder 10 of the internal combustion engine, which isshown schematically in FIG. 1, has a combustion chamber 11 defined by areciprocating piston 12, on the side, and by a cylinder head 13 of thecombustion cylinder 10, on the other side. The cylinder head 13 has aninlet chamber 14, with an inlet valve 15 at the end of the inlet chamberwhich is adjacent to combustion chamber 11 and an outlet chamber 16 withan outlet valve 17 at the outlet chamber end which is adjacent to thecombustion chamber 11. The inlet chamber 14 is connected to an exhaustmanifold 19, possibly by an intermediate outlet connection piece. Inaddition, a spark plug 20 projecting into the combustion chamber 11 isscrewed into the cylinder head 13. The spark plug 20 is constructed as aspecial spark plug. A translucent rod, through which the light emissionin the combustion chamber 11 and its configuration can be detected, isinstalled in its center electrode. The spark plug 20 is connected with ahigh-voltage ignition device 22 which is only indicated in a schematicmanner. Moreover, an injection nozzle 21, which projects into the inletchamber 14, is arranged in the cylinder head 13. A distributor fuelinjection pump designated by 23 injects a predetermined quantity of fuelinto the inlet chamber 14 via the injection nozzle 21. A total of fouridentically constructed combustion cylinders 10 with cylinder heads 13are provided in a four-cylinder internal combustion engine, all of whichcombustion cylinders 10 are connected to the intake manifold 18 and tothe exhaust manifold 19.

In order to achieve a low emission of pollutants, the internalcombustion engine is equipped with an exhaust recycling system 24. Therecycling system 24 comprises an exhaust return line 25, which branchesoff from the exhaust manifold 19 and can be constructed e.g. as aspecial steel tube. A header reservoir 26, is connected with the exhaustreturn line 25. An exhaust return line 27 leads from the headerreservoir 26 to the cylinder 10. The exhaust return line 27 leads intothe inlet chamber 14 in the cylinder head 13 of the combustion cylinder10 and ends there in a so-called turbulence nozzle whose opening isarranged immediately at the inlet valve 15. Such turbulence nozzles 28are known and are used in internal combustion engines for supplyingby-pass air to the combustion chamber of the combustion cylinders. Theturbulence nozzle consists a curved tube with an outlet opening actingas a throttle. A throttle valve 29 is arranged at the place where theexhaust return line 25 opens into the header reservoir 26, and serves asa first metering member for the recycling portion of the exhaust. Thethrottle valve 29 is connected via a coupling rod 30 with an airthrottle valve 31 which is arranged in a conventional manner in anair-intake connection piece 32 connected upstream of the intake pipe 18and is adjusted via the accelerator pedal. In carburetor engines, thisthrottle valve 31 is arranged in the carburetor, which fits in thislocation, and is designated as carburetor throttle valve. The throttlevalve 29 is also adjusted in a synchronous manner with the adjustment ofthe air throttle valve 31, wherein in the lower pressure range in theintake manifold 18 the exhaust recycling portion, which is fed into theheader reservoir 26 and then, via the turbulence nozzle 28, to therespective combustion cylinder 10, first increases sharply from zero asthe intake pipe pressure increases. After a predetermined position ofthe air throttle valve 31, the throttle valve 29 is completely openedand is, accordingly, without effect as metering member. The meteredexhaust recycling portion is now only determined by the turbulencenozzle 28 forming a second metering member, wherein the metered amountscontinuously decreases as the intake pipe pressure increases.

For optimal adjustment of the ignition angle α_(Z) and the fuel quantitywhich is injected via the injection nozzle 21 and determined by theinjection period t_(i), an electronic control device 33 is providedwhich control these two quantities in accordance with the operatingparameters of the internal combustion engine. Such parameters are theposition α_(DK) of the air throttle valve 31, the speed n of th internalcombustion engine, the combustion chamber temperature which is detectedby means of the temperature θ_(W) of the coolant water flowing throughthe cylinder head 13, the light configuration in the combustion chamber11, and the air index λ which is measured with a lambda prove 34arranged in the exhaust manifold 19. The injection period t_(i) and theignition angle α_(Z), i.e. the ignition time with reference to the crankangle, are adjusted by the control device 33 in such a way that thecombustion position is optimal, i.e. a maximum of energy conversion isachieved, and the air index in the exhaust λ=1. The lowest possibleemission values are accordingly achieved with a catalytic convertorconnected to the exhaust manifold 19.

In the second embodiment shown in FIG. 2, some portions of the exhaustrecycling system 24 are modified. The internal combustion engine itselfis unchanged. But identical structural component parts are increased by100 with respect to the exhaust recycling system.

In contrast to the exhaust recycling system in FIG. 1, the firstmetering member is not formed as a throttle valve in the exhaustrecycling system 124 according to FIG. 2, but as a metering valve 135which is arranged in the vicinity of the branching off of the exhaustreturn line 125 from the intake manifold 18, and the exhaust return line125 is divided into an extremely short line segment 136 to the exhaustmanifold 19, and a longer line segment 137 connected with the headerreservoir 126. Additional short exhaust return lines 127 lead from theheader reservoir 126 to the individual turbulence nozzles 128 which arearranged directly at every inlet valve 15 in the same manner as in FIG.1.

The metering valve 135 comprises two valve portions 138 and 139, thevalve portion 138 being connected with the line segment 136 and thevalve portion 139 being connected with the line segment 137. The twovalve portions 138 and 139 communicate with one another via a valveopening 140 which is controlled by a valve member 141 which cooperateswith a valve seat 142 surrounding the valve opening 140. The valve seat142 is annular the valve member 141 engaging the latter includes aconical closing body 143 biased by a valve closing spring 144 to itsunactuated basic position. The valve member 141 is connected with theair throttle valve 31 via a Bowden cable or is immediately connectedwith the accelerator pedal indicated by a double arrow 48. The meteringvalve 135 works in the same manner as the throttle valve 29 in FIG. 1.By shifting the metering valve 135 directly into the high temperaturerange of the exhaust manifold 19, hotter exhaust gases flow through itthan those flowing through the throttle valve 29 in FIG. 1, so thatfewer soot and condensation deposits occur. Accordingly, the change inthe exhaust recycling a mount metered in the same valve member position,which change is caused by such deposits, is substantially smaller.

A valve 146, with which the inlet of the exhaust return line 125 can beclosed or opened, is additionally arranged in the line segment 136between the metering valve 135 and the exhaust manifold 19. The valve146 is controlled by a bimetal 147 in such a way that it keeps theexhaust return line 125 closed below a predetermined temperature of theexhaust flow and opens it above this allowed temperature. The exhaustrecycling is accordingly block during the hot-running of the internalcombustion engine.

In addition, in FIG. 2, a check valve 51 which opens in the direction ofthe combustion chamber 11 and is formed as a flap valve, or as adiaphragm valve is arranged in each of the intake pipes 50 leading fromthe intake manifold 18 to the individual cylinders and combustionchamber 11, respectively, of the internal combustion engine. This checkvalve is arranged upstream of the injection nozzle in each instance andit is, accordingly, prevented that no recycled exhaust can be guided tothe cylinder which is currently executing an intake stroke from theintake pipes 50 which are not connected at the moment to the respectivecombustion chamber 11 via the inlet valve 15. It is accordingly achievedthat the recycling exhaust is always fed exclusively via the turbulencenozzle which is assigned to the respective cylinder executing an intakestroke. This increases the discharge speed and accordingly theturbulence and preparation of the fuel which is introduced into thesucked-in air flow via the injection nozzle 21. Of course, thisconstruction can also be used in the embodiment according to FIG. 1 oralso in carburetor internal combustion engine providing analogousadvantage.

In constrast to the above arrangement, a header reservoir 226 shown inFIG. 3, replaces the header reservoir 26 and 126, respectively, of theembodiments according to FIGS. 1 and 2. The header reservoir 226includes a closed circular cylinder, the exhaust return line 25 and 125,respectively, entering on one end face 53 of the circular cylinder andthe separate exhaust return lines 27, 127 leading away on the other endface 54 of the closed circular cylinder. These exhaust return lines arearranged in the circuit at regular intervals and in the intake sequenceof the combustion chambers assigned to them. A drive shaft 55 leadsaxially through the header reservoir 226, projects outward at one endface 53, and is driven in this location via the crankshaft of theinternal combustion engine or its camshaft and is supported on the otherside in the other end face 54. The drive shaft comprises a valve disk 56tightly adjoining the inside of the other end face 54, which valve disk56 covers the entire inside of the other end face 54 and comprises acontrol opening 57 through which each of the exhaust return lines 27communicates with the interior space of the header reservoir 226 oneafter the other during the rotation of drive shaft 54. This valve disk56 with drive shaft 55 constitutes a distributor 58 by which, dependingon the rotational position of the valve disk, the exhaust flow fed viathe exhaust return line 25, is guided further into the respectivecylinder executing the intake stroke.

In an alternative embodiment to that of FIG. 3, the header reservoir326, as shown in FIG. 4, is likewise constructed in a circularcylindrical manner. Only the exhaust return line 25, 125 open coaxiallyinto the latter, and the exhaust return lines 27, 127 lead from thecircumferential wall 59 of the header reservoir 326. A cup-shaped body,which covers the inside of the circumferential wall 59 of the headerreservoir with its circumferential wall 60 and controls the individualexhaust return lines 25, 125 with a control opening 157 analogous to theconstruction according to FIG. 3, is provided here as a valve disk 156.The cup-shaped valve disk 156 is moved by a drive shaft guided throughthe end face of the header reservoir synchronously relative to the speedof the internal combustion engine.

In these embodiments, the exact exhaust recycling quantity is meteredexclusively to that turbulence nozzle 28, 128 which is assigned to therespective cylinder executing an intake stroke. An optimal exhaustinflow velocity is adjusted at the turbulence nozzle, and any faultymetering or shifting forward of the exhaust recycling quantity isavoided in other cylinders which do not execute an intake stroke. Inaddition, the gas quantity fed to the burner can flow in without beingimpeded, which improves the density of the charge in the combustionchamber in comparison to the embodiment of FIG. 2.

While the invention has been illustrated and described as embodied in aninternal combustion engine, particularly Otto engine, it is not intendedto be limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. An internal combustion engineparticularly Otto engine comprising:an intake manifold including athrottle valve for controlling air flow therein; an exhaust manifold; aplurality of combustion cylinders, each combustion cylinder having acombustion chamber, an inlet chamber communicating with said intakemanifold, an inlet valve for communicating said inlet chamber with saidcombustion chamber, an outlet chamber communicating with said exhaustmanifold, and an outlet valve for communicating said combustion chamberwith said outlet chamber; exhaust recycling means comprising an exhaustreturn line connected with said exhaust manifold, an exhaust meteringdevice communicating with said exhaust return line and including a firstmetering member actuatable jointly with said throttle valve of saidintake manifold, and a second metering member located downstream of saidfirst metering member and including a plurality of turbulence nozzlescorresponding to said plurality of combustion cylinders, each of saidturbulence nozzles being located immediately adjacent to a respectiveinlet valve of a respective combustion cylinder, said exhaust recyclingmeans further comprising a header reservoir located downstream of saidfirst metering member, and a plurality of separate exhaust return linesconnecting said header reservoir with said plurality of turbulencenozzles; and a plurality of intake tubes for communicating said intakemanifold with said plurality of combustion cylinders, each intake tubecomprising an inlet opening communicating with a respective inletchamber of a respective combustion cylinder and a check valve locatedupstream of said inlet opening for preventing backflow from said inletchamber into said intake manifold.
 2. An internal combustion engineaccording to claim 1, wherein said check valve is a diaphragm valve. 3.An internal combustion engine particularly Otto engine comprising:anintake manifold including a throttle valve for controlling air flowtherein; an exhaust manifold; a plurality of combustion cylinders, eachcombustion cylinder having a combustion chamber, an inlet chambercommunicating with said intake manifold, an inlet valve forcommunicating said inlet chamber with said combustion chamber, an outletchamber communicating with said exhaust manifold, and an outlet valvefor communicating said combustion chamber with said outlet chamber;exhaust recycling means comprising an exhaust return line connected withsaid exhaust manifold, an exhaust metering device communicating withsaid exhaust return line and including a first metering memberactuatable jointly with said throttle valve of said intake manifold, anda second metering member located downstream of said first meteringmember and including a plurality of turbulence nozzles corresponding tosaid plurality of combustion cylinders, each of said turbulence nozzlesbeing located immediately adjacent to a respective inlet valve of arespective combustion cylinder, said exhaust recycling means furthercomprising a header reservoir located downstream of said first meteringmember, a plurality of separate exhaust return lines connecting saidheader reservoir with said plurality of turbulence nozzles, said exhaustrecycling means comprising a distributor connected with said headerreservoir, and means drivable by the internal combustion engine fordriving said distributor synchronously relative to the internalcombustion engine, said distributor communicating separate exhaustreturn lines only with a respective cylinder executing an intake strokein an intake sequence of said combustion cylinders of the internalcombustion engine.
 4. An internal combustion engine according to claim3, wherein said header reservoir has a circular end face, saiddistributor comprising a valve disk covering said circular end face ofsaid header reservoir, said valve disk having a control opening and isrotatable to connect a respective separate exhaust return line with saidheader reservoir in the intake sequence of respective combustioncylinders associated with said separate exhaust return line.
 5. Aninternal combustion engine according to claim 3, wherein said headerreservoir has a circumferential wall, said distributor comprising acup-shaped valve disk driven synchronously relative to the internalcombustion engine and having a circumferential wall in contact with saidcircumferential wall of said header reservoir, said valve disccomprising a control opening communicating with said separate exhaustreturn line in accordance with the intake sequence of the respectivecombustion cylinders associated with said separate exhaust return lines.6. An internal combustion engine particularly Otto engine comprising:anintake manifold including a throttle valve for controlling air flowtherein; an exhaust manifold; a plurality of combustion cylinders, eachcombustion cylinder having a combustion chamber, an inlet chambercommunicating with said intake manifold, an inlet valve forcommunicating with inlet chamber with said combustion chamber, an outletchamber communicating with said exhaust manifold, and an outlet valvefor communicating said combustion chamber with said outlet chamber;exhaust recycling means comprising an exhaust return line connected withsaid exhaust manifold, an exhaust metering device communicating withsaid exhaust return line and including a first metering memberactuatable jointly with said throttle valve of said intake manifold, anda second metering member located downstream of said first meteringmember and including a plurality of turbulence nozzles corresponding tosaid plurality of combustion cylinders, each of said turbulence nozzlesbeing located immediately adjacent to a respective inlet valve of arespective combustion cylinder, said exhaust recycling means furthercomprising a header reservoir located downstream of said first meteringmember, and a plurality of separate exhaust return lines connecting saidheader reservoir with said plurality of turbulence nozzles, saidmetering member being located in an immediate vicinity of said exhaustmanifold.
 7. An internal combustion engine particularly Otto enginecomprising:an intake manifold including a throttle valve for controllingair flow therein; an exhaust manifold; a plurality of combustioncylinders, each combustion cylinder having a combustion chamber, aninlet chamber communicating with said intake manifold, an inlet valvefor communicating said inlet chamber with said combustion chamber, anoutlet chamber communicating with said exhaust manifold, and an outletvalve for communicating said combustion chamber with said outletchamber; exhaust recycling means comprising an exhaust return lineconnected with said exhaust manifold, an exhaust metering devicecommunicating with said exhaust return line and including a firstmetering member actuatable jointly with said throttle valve of saidintake manifold, and a second metering member located downstream of saidfirst metering member and including a plurality of turbulence nozzlescorresponding to said plurality of combustion cylinders, each of saidturbulence nozzles being located immediately adjacent to a respectiveinlet valve of a respective combustion cylinder, said exhaust recyclingmeans further comprising a header reservoir located downstream of saidfirst metering member, and a plurality of separate exhaust return linesconnecting said header reservoir with said plurality of turbulencenozzles; an ignition time of a combustion mixture in the combustionchamber of each of said combustion cylinders being controlled to anoptimal combustion position, and the ignition in the combustion chamberof each of said combustion cylinders being controlled to the optimalcombustion position independently of optimal combustion position controlof others of said combustion cylinders.
 8. An internal combustion engineaccording to claim 7, further comprising an electronic control devicefor controlling an ignition angle and an injection period of fuelinjected in respective cylinders in accordance with a position of saidthrottle valve of said intake manifold, speed of the internal combustionengine, air index, coolant water temperature measured at a cylinderheads of respective combustion cylinders and a combustion configurationof respective combustion chambers of respective combustion cylinders. 9.An internal combustion engine according to claim 8, wherein each of saidcombustion cylinders comprises a spark plug for providing a respectivecombustion chamber light configuration to be optically detected.
 10. Aninternal combustion engine according to claim 9, further comprising acatalytic converter connected with said exhaust manifold, saidelectronic control device adjusting the ignition angle and the fuel-airmixture produced by a carburetor in such a way that the air index (λ) isregulated to
 1. 11. An internal combustion engine according to claim 9,further comprising a catalytic converter connected with said exhaustmanifold, said electronic control device controlling the ignition angleand the fuel-air mixture produced by an injection nozzle in such a waythat the air index (λ) is controlled to
 1. 12. An internal combustionengine particularly Otto engine comprising:an intake manifold includinga throttle valve for controlling air flow therein; an exhaust manifold;a plurality of combustion cylinders, each combustion cylinder having acombustion chamber, an inlet chamber communicating with said intakemanifold, an inlet valve for communicating said inlet chamber with saidcombustion chamber, an outlet chamber communicating with said exhaustmanifold, and an outlet valve for communicating said combustion chamberwith said outlet chamber; exhaust recycling means comprising an exhaustreturn line connected with said exhaust manifold, an exhaust meteringdevice communicating with said exhaust return line and including a firstmetering member actuatable jointly with said throttle valve of saidintake manifold, and a second metering member located downstream of saidfirst metering member and including a plurality of turbulence nozzlescorresponding to said plurality of combustion cylinders, each of saidturbulence nozzles being located immediately adjacent to a respectiveinlet valve of a respective combustion cylinder, said exhaust recyclingmeans further comprising a header reservoir located downstream of saidfirst metering member, and a plurality of separate exhaust return linesconnecting said header reservoir with said plurality of turbulencenozzles, said first metering member being formed as a mechanicallyactuatable metering valve connected with one of said throttle valves ofsaid intake manifold and accelerator pedal with a Bowden cable.
 13. Aninternal combustion engine according to claim 12, wherein said exhaustreturn line has a first line segment connected with said exhaustmanifold and a second line segment connected with said header reservoir,said metering valve being located between said second line segments andincluding first and second valve portions, a valve opening communicatingsaid first and second valve portions, a valve seat enclosing said valveopening, a valve member cooperating with said valve seat forcommunicating said first and second valve portions through said valveopening, and a valve spring for biasing said valve member in a closingdirection thereof, said valve member being connected with said Bowdencable acting on said valve member in an opening direction thereof. 14.An internal combustion engine according to claim 13, wherein said valveseat is an annular valve seat, and said valve member comprises a conicalvalve closing member cooperating with said annular valve seat.
 15. Aninternal combustion engine according to claim 12, wherein said saidmetering valve is located in said exhaust return line, said exhaustreturn line comprising a very short first line segment communicatingbetween said metering valve and said exhaust manifold, each of saidseparate exhaust return lines comprising a very short exhaust returnportion for communicating said header reservoir with a respectiveturbulence nozzle.